Method and apparatus for casting



NOV. 4 1924. 1,514,530

| J. KEMP METHOD AND APPARATUS FOR CASTING Filed Aug. 21 1922 2 SheetsSheet 1 Nov. 4 1924. 1,514,530

L. J. KEMP METHOD AND APPARATUS FOR CASTING Filed Aug. 21, 1922 2 Sheets-Shes- 2 /2, a; r /0. m

. 5 /i2o/Q Patented Nov. 4, 1924.

UlTED STATES LEONARD JOHN KEMP, OF QUEENS'I'OWN, CAPE PROVINCE, SOUTH AFRICA.

amnion am) mum non casrme.

Application M August 21, 1922. Serial 110. 583,279.

To all whom it concern:

Be it known that I, LEONARD JOHN KEMP,

a subject of the King of Great Britain, residing at Queenstown, Cape Province, South Africa, have invented certain new and useful "Improvements in Methods and Apparatus for Casting, of which the following is a specification.

This invention relates to casting small objects in a mould, such as fillings for teeth or ornamental goods of metal or porcelain, as for instance a fly, which require very accurate deposit of the molten material in the mould.

The invention further refers to apparatus employed in casting operations of the character referred to. I

An object of the invention is to ensure an accurate flow of molten material into the mould so that every crevice is filled.

Another object is to provide a mould ring a suitable for holding the compound in which such small objects are moulded, the mould ring bein constructed so that it may be temporari y fixed within a furnace and the contents be subjected to pressure during the moulding operation.

.A further object of the invention is to con- .struct a furnace adapted to receive a mould for casting'small objects, the furnace beingconstructed so that pressure can be applied to the mouldand the molten material, while the latter is heated and during the flow of the melt.

A still further object is to construct a .furnace which, is removable from its base plate, the base plate being constructed so that the mould can be fixed thereupon, the arbe lifted fromor placed upon the base plate after the mould has .been fixed in position, therebv givin great facility for manipulating the moul and its contents, a further object of the invention being to provide an electrical furnace, the heat from which is controlled by varying the extent of the operative winding of the furnace.

In the accompanying drawings are illus-.

trated some preferred forms of the present invention, in which:

Fig. 1 illustrates diagrammatically in elevation a complete apparatus for carrying out the present invention;

Fig. 2 is a section on the line 2-2 of Fig. 1, to an enlarged scale;

in which a pressure below atmosphere is obtained, 2 being a nozzle connected to the tank and 3 the T piece connected to the nozzle, the T piece being associated with branches 4 and 5, the flow through which is controlled by valves-.6, 6, the branch 5 having a socket 7 engaged thereon the socket 7 being adapted to receive a nipple 8 carried by a circular perforated base plate 9, the base plate 9 being provided with suitable guides 10 for a furnace, the guides being preferably arranged at opposite ends of a diameter. On the base plate 9 is arranged a furnace comprised by a metal cylinder 11,'carrying an annulus of refractory material 12, in which is embedded, as indicated at 13, the coils for generating heat by electrical energy. The furnace is arranged vertically and has an opening at the top and at the bottom, the to opening being provided with a removab eclosure member 14, the furnace being also provided with sockets, preferably of tubular nature as indicated at 15 and formed with the exterior wall 11 of thev furnace,

"through which sockets the guides 10 of the base plate may protrude, the furnace being rangement being such that the furnace canfixed by operating set screws 16 carried in the sockets and adaptedto bite" into the ides, as will'be readily understood. It will be noted that the baseplate is a com pletely separate integer from its furnace which latter canbe entirely removed therefrom, and that the base plate includes the floor of the furnace.

A. packing member, such as an annular ring 17 may be arranged, as shown in Fig. 2, between the bottom of the furnace and the base plate 9. Within the furnace is arranged a mould ring 18 carrying investment compound 19, in which may be formed the mould indicated at 20 for a casting operation, the

' the base plate 9 is arranged a flexible seating washer 25, on which the mould ring is seated, the arrangement being such that if tension is applied to the arms 21 and considering the base plate 9 to be fixed, an air-tight joint will be obtained between the mould on and the moulds of ring and the base plate. In order to apply such tension draw bars 26 are disposed to engage the hooked extremities of the arms 21, the draw bars being connected by a cross bar 27 carrying athreaded member 28 adapted, on being rotated positively, to press against an end of the socket 7, which is recessed as indicated at 29 to receive said threaded member, further rotation of the threaded member results in tension being applied to the draw bars 26 through the medium of the cross bar 27, which is preferably provided with a boss, as indicated at 30, to extend the bearing surface of the threaded member 28.

The method of operation considering the apparatus to be used' for the manufacture of a filling for teeth, will be as follows A wax impression of the cavity in the tooth will be taken and then placed in a ring mould which will be afterwards packed with an investment compound as is well f known in the art. The whole will then be heated to run out the wax and leave a vent,

through which molten material may be poured into the mould so formed in the investment compound. The filling material, gold, porcelain, or the like, will then be placed over the vent in the investment compound and the ring mould will be fixed on the base plate 9 so that there is an air-tight joint between them.

The furnace will then be placed in position so that a required heat is obtainable, which will depend upon the material being melted; electrical energy will then be turned the furnace heated up to melt the casting material, and thenconnection will be effected between the base of the mould and the vacuum tank, that is, in the case illustrated, the valve 6 will be op- .erated and suction will then occur through the members 2, 3, 5, 7 and S and the opening 23 which isconnected to the base of the mould; the suction thus applied will cause air to be drawn through the investment compound and as the air is removed from the mould the molten material will flow in and completely fill the cavity formed in the mould, it being understood that as soon as the furnace is placed in position over the plate.

mould, the closure 14 is applied to prevent a i draught flowing up through the openings 24 and the interior of the furnace.

In order to vary the extent of the heating surface in the furnace the coils, indicated by the numeral 13, will be connectedin series and provided with leads 31, 32, 33, 34; the lead'31 is connected to supply and the leads 32, 33 and 34 are arranged in an arc to be covered at will by a rotatable switch member, diagrammatically illustrated at 35, itlself connected to the other terminal of sup- P Y According, therefore, to which of the loads 32, 33 or 34 that the switch arm 35 engages, godthe extent of coils in operation is modi- A further variation of the current supply to the coils, whatever extent is being used, is obtained by introducing a rheostat, as indicated at 36, on the main, as will be well understood in the art.

Referring now to the modified construction shown in Fig. 4, which is operable to carry out the method of operation described with reference to Figs. 1, 2 and 3, a base plate 37 is provided with an integral nipple 38, and is perforated centrally as indicated at 39, the nipple38 carrying a threaded sleeve 40 adapted to fit into a socket member such as 7, the member 10 being bored in extension of the opening 39 of the base The base plate is provided with a peripheral flange al and carries a flexible ring or washer 42, on which is disposed the urnace, constructed similarly to that already referred to,

vided with sockets 43 and draw bars 4 1 associated with threaded members 45 adapted to operate against the base plate 37, which is provided with abutment plates 46 for that purpose. It will be obvious, therefore, that on rotation of the threaded members 45, the furnace will be drawn tightly on to the flexible member 42, thereby obtaining an airtight joint between the bottom of the fur mace and the base plate. p

In this construction the refractory n1ateri'al 12 of the furnace is extended to form a bottom to the furnace, the bottom part being perforated, as indicated at 47, in order to provide an opening opposite to the opening 39 of the base plate; 011 the bottom of the furnace being prothe furnace so formed is arranged a flexible push said an air-tight joint between the ring mould and the bottom of the furnace.

With such a construction-it will be obvious that a negative pressure can be applied through the member 40, the opening 39, the opening 47 and to the bottom of the mould, with the resulting withdrawal of the air in the mould, as already explained. The means for regulating the heat of the furnace in this construction may be the same as that already referred to with reference to the construction shown in Fig. 1.-

By the present invention completely accurate articles can be cast from porcelain in view of the fact that pressure as well as heat is involved inthe operation and that the heat can be closely regulated.

The apparatus is equally useful for east ing in metals more easily melted, as for instance gold.

I claim 1. In casting apparatus, the combination of a vertical furnace, a base plate for said furnace completely separate therefrom, clamping means for securing said furnace to said base plate, a mould ring, a'support therefor, arms on said mould ring, means for applying pressure through said arms to mould ring on to its support, and a conduit, through said support, connecting the bottom of said mould to a vaccum tank, whereby air may be withdrawn from the mould as the molten metal flows thereinto.

2. In casting apparatus, the combination of a vertical furnace, a perforated base plate completely separate therefrom and including the floor of the furnace, vertical guides on said base plate for said furnace, a mould ring supported on the base plate, arms extending from said mould ring through said base plate, adjustable means for straining said arms to clamp the mould ring on the base plate, and a'conduit, through said base plate, connecting the bottom of the mould to a vaccum tank, whereby air may be withdrawn from the mould as the molten metal flows thereinto.

3. In casting apparatus, the combination of a vertical furnace, a perforated base plate completely separate therefrom and including the floor of the furnace, vertical guides on said base plate for said furnace, means for fixing said furnace in various positions on said guides, a mould rin supported on said base plate, arms exten ing from said mould ring through said base plate, means connecting said arms to an adjustable tension member for clamping the mould ring on the base plate, and a conduit, through said base plate, connecting the bottom of said mould to a vaccum tank, whereby air may be withdrawn. from the mould, as the molten metal flows thereinto.

4. In casting apparatus, the combination of a vertical furnace, a perforated base plate completely separate therefrom, and including the floor of the furnace, vertical guides on said base plate for said furnace, means for fixing said furnace in various positions on said guides, a mould ring supported on said base plate, hooked arms depending from said mould ring through said base plate, a flexible perforated washer interposed between said base plate and the bottom of said mould ring, draw bars engaging the hooked arms, a threaded member, a cross bar on said threaded member, a fixed abutment, said threaded member being rotatable against said fixed abutment to operate the draw bars and clamp the mould ring on the washer, and a conduit, through said base plate and washer,,connecting the bottom of the mould to a vacuum tank.

5. In casting apparatus, the combination of a vertical electrical furnace having an opening at the top and at the bottom, a perforated base plate completely separate therefrom including the floor of the furnace and an opening concentric with the opening at the bottom of the furnace, sockets on said furnace and vertical guides on said base plate for said sockets, adjusters fitted to said sock'ets for fixing the furnace in various positions on said guides, a removable closure for the opening at the top of said furnace, a mould ring supported on the base plate over the opening therein, hooked arms depending from said mould ring through said base plate, a flexible perforated washer interposed between said base late and the bottom of said mould ring, gaging the hooked arms, a threaded member, a cross bar on said threaded member, a fixed abutment, said threaded member being rotatable against said fixed abutment to operate the draw bars and clamp the mould ring on the washer,'and a conduit, through said base plate and washer connecting the bottom of the mould to a vacuum tank.

6. A mould ring having depending arms, each formed at the free extremity with a hook.

In testimony whereof I afiix my signature.

vLEONARD JOHN KEMP.

raw bars en-,- 

